The present invention relates to a cutting tool for chip removing machining. The tool comprises a tool body which has a shank, at least one chip gullet, at least one insert-receiving site arranged in the working end of the tool body, and a cutting portion. The cutting portion consists of at least two cutting inserts assembled in the working end of the tool, one of which consists of a material which has a different hardness relative to another cutting insert. The cutting edges of the cutting inserts transites mainly continuously straight into each other.
Hitherto known drills which have two cutting inserts brazed into the working end of the drill, have cutting inserts of equal hardness along the cutting edge in the radial direction of the drill. The material in both of the cutting inserts is a compromise between a soft material which has an excellent resistance to compressive stress arising in the centre of the drill and a hard material which has an excellent resistance to the high cutting speed arising in the periphery of the drill. The material chosen for the cutting inserts thus is one which is fairly resistant to compressive stress and which is fairly resistant to high cutting speed, and therefore the cutting edge of the drill will not have an optimum working life. The joint between these two cutting inserts is centrally positioned in the drill which reduces the strength of the centre.
An object with the present invention is to provide a cutting tool whose cutting inserts are of different hardness in order to achieve an optimized cutting result.
Another object is to arrange joints between the cutting inserts such that the soldering result is optimized.
Still another object is to arrange the joint such that the joint will not impact on the work piece surface.
These and other objects are achieved by a cutting tool according to the present invention.